Extendable guide rail for a bellows type camera

Abstract

A composite guide rail for bellows type cameras is disclosed in which the composite rail is comprised of two rail pieces. A multi-fingered connecting insert has a base secured to the end of the first rail while the fingers conform to an inner cavity in one end of the second rail and can be slidably inserted-therein. A wedge having a threaded central bore is movably disposed between the plurality of fingers and is connected to a thumb screw by a threaded connecting rod, the thumb screw located at the opposite end of the first rail from the connecting insert. When the fingers are inserted into the cavity of the second rail and the thumbscrew turned in one direction, the fingers are expanded by the wedge being drawn therebetween such that the fingers come into pressing engagement with the walls defining the inner cavity of the second rail. When assembled, the first and second rails take on the aspect of a single rail.

I claim: 
     
       1. For a photographic bellows type camera having an image carrier standard and a lens carrier standard which are movable with respect to one another, a composite guide rail to which the image carrier standard and lens carrier standard are slidably mounted, the composite guide rail comprising: a main section of a desired length having inner walls forming a cavity at a connecting end of the main section length;   a separate extension section of a desired length having a cavity at the connecting end of the extension section length;   an expansion fork including a body and at least two fingers, the body fitting into the cavity in the connecting end of the extension section length, and connected to the extension section, and the at least two fingers slidably fitting into the main section cavity; and   means for releasably separating from one another the at least two fingers, whereby, when the at least two fingers of the expansion fork are inserted in the main section cavity, with separation of the at least two fingers from one another, the at least two fingers engage the inner walls of the main section cavity locking the main section and the extension section to one another and, with release of separation of the at least two fingers from one another, the at least two fingers disengage from the inner walls of the main section cavity, unlocking the main section and the extension section from one another and allowing the extension section, with the connected expansion fork, to be removed from the main section.     
     
     
       2. The composite guide rail of claim 1, in which the outer surfaces of the expansion fingers are complimentary in configuration to the inner walls of the guide rail main section. 
     
     
       3. The composite guide rail of claim 2, in which the at least two fingers have inside surfaces which collectively define a first bore of a desired configuration opening at the distal ends of the at least two fingers and in which the separating means is comprised of a wedge having an outer configuration complementary to the first bore. 
     
     
       4. The composite guide rail of claim 3, in which the separating means is further comprised of means to draw the wedge into the first bore. 
     
     
       5. The composite guide rail of claim 4, in which the means to draw the wedge into the first bore comprises: a second bore extending through the expansion fork body approximately concentric with the centerline of the length of the guide rail extension section;   a third bore in the wedge approximately concentric with the centerline of the length of the guide rail extension section; and   a shaft passing through the second bore and connected to the wedge along the third bore by which the wedge is translatable between a first position in the first bore and a second position in the first bore.   
     
     
       6. The composite guide rail of claim 5, in which the connection between the shaft and the wedge comprise complementary threads along the third bore and along the length of the shaft interacting with the third bore, and a retainer means which prevents translation of the shaft with respect to the length of the guide rail extension section, whereby rotation of the shaft in one direction draws the wedge deeper into the first bore and rotation of the shaft in the opposite direction forces the wedge along the first bore toward the terminal ends of the fingers. 
     
     
       7. The composite guide rail of claim 6, in which the first bore is tapered complementary to the taper of the wedge such that the wedge and the bore interact over more than a line of contact. 
     
     
       8. The composite guide rail of claim 7, in which the at least two fingers comprise two fingers, each finger slightly less than half the thickness of the expansion fork body to thereby define a gap of generally consistent dimension from one side of the expansion fork to the other extending to the proximal ends of the two fingers. 
     
     
       9. The composite guide rail of claim 8, in which the means to draw the wedge into the first bore further comprises a knob staked to one end of the shaft. 
     
     
       10. The composite guide rail of claim 9, in which the connecting end of the guide rail base section and the connecting end of the guide rail extension section are shaped such that, upon engagement, the base section and the extension section take on the aspect of a single guide rail. 
     
     
       11. For a photographic bellows type camera having an image carrier standard and a lens carrier standard which are movable with respect to one another, a composite guide rail to which the image carrier standard and lens carrier standard are slidably mounted, the composite guide rail comprising: a main section of a desired length having inner walls defining a cavity at a connecting end of the main section length;   a separate extension section Of a desired length having, at a connecting end of the extension section length, an expansion fork having at least two fingers, the two fingers insertable into the main section cavity and having inside surfaces which collectively define a first bore of a desired configuration opening at the distal ends of the two fingers;   a wedge occupying at least a portion of the first bore;   a second bore extending through the expansion fork approximately concentric with the first bore;   a third bore in the wedge approximately concentric with the centerline of the wedge;   a shaft passing through the second bore and connected to the wedge along the third bore by which the wedge is translatable;   the connection between the shaft and the wedge comprise complementary threads along the third bore and along a portion of the length of the shaft which interacts with the third bore;   a retainer means which prevents translation of the shaft with respect to the length of the guide rail extension section between a first position in the first bore and a second position in the first bore; and   a knob staked to the end of the shaft opposite the threaded portion, whereby, when the two fingers of the expansion fork are inserted in the main section cavity, turning the knob in one direction causes the wedge to translate along the shaft toward the knob causing the wedge to move deeper into the first bore which causes the two fingers to move apart from one another and causes the two fingers to engage the main section cavity inner walls to lock the guide rail extension section to the guide rail main section.     
     
     
       12. The composite guide rail of claim 11, in which the wedge is a frustrum. 
     
     
       13. The composite guide rail of claim 12, in which the connecting end of the guide rail base section and the connecting end of the guide rail extension section are shaped such that, upon engagement, the base section and the extension section take on the aspect of a single guide rail. 
     
     
       14. For a photographic bellows type camera having an image carrier standard and a lens carrier standard which are movable with respect to one another, a composite guide rail to which the image carrier standard and lens carrier standard are slidably mounted, the composite guide rail comprising: a main section of a desired length having inner walls defining a cavity at a connecting end of the main section length;   a separate extension section of a desired length having at a connecting end of the extension section length an expansion fork having at least two fingers, the at least two fingers insertable into the main section cavity; and   means for varying the distance between the at least two fingers, whereby, when the at least two fingers of the expansion fork are inserted in the main section cavity and the distance between the at least two fingers is increased, the at least two fingers engage the main section cavity inner walls.     
     
     
       15. The composite rail of claim 14, in which the at least two fingers aproximate the length of the guide rail main section and the main section cavity is of sufficient depth to permit insertion of the at least two fingers, whereby, the at least two fingers permit the total length of the composite guide rail to be greater than the sum of the lengths of the main section and the extension section by having some portion of the fingers outside the main section cavity when engaged. 
     
     
       16. A connection device for connecting a first rail to a second rail, said first rail having a first connecting end and a first rail cavity defined by a first rail inner surface opening on the first connecting end and extending inwardly therefrom a distance along the length of the rail, and said second rail having a second connecting end and a second rail cavity defined by a second rail inner surface opening on the second connecting end and extending inwardly therefrom a distance along the length of the said second rail, said connection device comprising: an insert having a first end conforming to the configuration and dimension of said first rail cavity whereby said first end fits snugly within said first rail cavity;   connecting means whereby said first end of said insert is held in place in said first rail cavity;   said insert having a second end defined by a plurality of fingers which extend away from said first end, said fingers in the aggregate conforming to the configuration and dimension of said second rail cavity whereby said second end slidably and removably fits within said first rail cavity;   a wedge interposed between said second end plurality of fingers; and   means for selectively drawing said wedge toward said insert first end and distancing said wedge away from said insert first end, whereby said plurality of fingers are forced outwardly when said wedge is moved in one direction relative to said insert first end such that said plurality of fingers are further separated from one another and come into pressing engagement with the first rail inner surface to connect said first rail to said second rail and whereby said plurality of fingers return to an at rest position when said wedge is moved in the opposite direction relative to said insert first end such that said plurality of fingers release pressing engagement with the first rail inner surface to disconnect said first rail from said second rail.